Anti-immunoglobulin kappa variable 4-1 antibodies are used for the immunodetection of the protein encoded by the IGKV4-1 gene. In humans, the canonical protein has a reported length of 121 amino acid residues and a mass of 13.4 kDa. Its subcellular localization is in the cell membrane and is secreted. It is noted to be involved in adaptive immune responses.